PREMATURE TRANSLATION OF OSKAR IN OOCYTES LACKING THE RNA-BINDING PROTEIN BICAUDAL-C

Bicaudal-C (Bic-C) is required during Drosophila melanogaster oogenesi s for several processes, including anterior-posterior patterning. The gene encodes a protein with five copies of the KH domain, a motif foun d in a number of RNA-binding proteins. Using antibodies raised against the BIC-C protein, we show that multiple isoforms of the protein exis t in ovaries and that the protein, like the RNA, accumulates in the de veloping oocyte early in oogenesis. BIC-C protein expressed in mammali an cells can bind RNA in vitro, and a point mutation in one of the KH domains that causes a strong Bic-C phenotype weakens this binding. In addition, oskar translation commences prior to posterior localization of oskar RNA in Bic-C- oocytes, indicating that Bic-C may regulate osk ar translation during oogenesis.